Effect of the doping level on the conductance of polymer-salts complexes in the presence of humidity

The conductance of complexes between polyacetylene-based polymers and inorganic salts (dopants) was investigated in the presence of humidity as a function of the salt concentration. The conductance reaches a maximum value by increasing the doping level. The decrease of conductance observed for high-doping values is due to enhanced ion interactions. In some cases, the conductance/doping plots show two maxima likely due to ion association, i.e. to the formation of double and triple ions. The trends of conductance and capacitance with the doping are very similar at constant relative humidity. This supports a previously suggested model, based on the assumption that films of polymer electrolytes behave, in the presence of humidity, as solid polymer structures surrounded by a liquid ion solution. (C) 2003 Elsevier B.V. All rights reserved.